Kinetic measurement of the step size of DNA unwinding by Escherichia coli UvrD helicase

被引：224

作者：

Ali, JA ^{[1
]}

Lohman, TM ^{[1
]}

机构：

[1] WASHINGTON UNIV,SCH MED,DEPT BIOCHEM & MOL BIOPHYS,ST LOUIS,MO 63110

来源：

SCIENCE | 1997年 / 275卷 / 5298期

关键词：

D O I：

10.1126/science.275.5298.377

中图分类号：

O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];

学科分类号：

07 ; 0710 ; 09 ;

摘要：

The kinetic mechanism by which the DNA repair helicase UvrD of Escherichia coli unwinds duplex DNA was examined with the use of a series of oligodeoxynucleotides with duplex regions ranging from 10 to 40 base pairs. Single-turnover unwinding experiments showed distinct lag phases that increased with duplex length because partially unwound DNA intermediate states are highly populated during unwinding. Analysis of these kinetics indicates that UvrD unwinds duplex DNA in discrete steps, with an average ''step size'' of 4 to 5 base pairs (approximately one-half turn of the DNA helix). This suggests an unwinding mechanism in which alternating subunits of the dimeric helicase interact directly with duplex DNA.

引用

页码：377 / 380

页数：4

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